Cutting insert for high feed face milling

Abstract

A cutting insert for milling operations, such as, face milling, slot milling, plunge milling, and ramping operations. The cutting insert exhibits a combination of favorable cutting-edge strength, and unique cutting-edge geometry to allow milling operations at relatively high feed rates. The cutting insert includes at least four convex cutting edges. Certain embodiments of square cutting inserts will have four convex cutting edges connected by nose corner regions. Each convex cutting edge includes a first curved cutting-edge region having a radius greater than or equal to two times a radius of the largest circle that may be inscribed on the top surface. Each convex cutting edge also includes a second curved cutting-edge region adjacent the first curved cutting-edge region and having a radius less than or equal to the diameter of the inscribed circle. Each convex cutting edge may also include one or more straight cutting-edge regions.

1 . A cutting insert, comprising:
 a top surface;   a bottom surface with a perimeter that is less than a perimeter of the top surface;   a plurality of side surfaces connecting the top surface and the bottom surface;   a convex cutting edge formed at an intersection between each side surface and the top surface; and   a nose corner region connecting adjacent convex cutting edges,   wherein each convex cutting edge comprises a first curved cutting-edge region formed with a radius greater than or equal to a radius of the largest circle that may be inscribed on the top surface, and   wherein each convex cutting edge comprises a second curved cutting-edge region disposed between the first curved cutting-edge region and the nose corner region, the second curved cutting-edge region formed with a radius less or equal to a diameter of the largest circle that may be inscribed on the top surface.   
     
     
         2 . The cutting insert of  claim 1 , further comprising a first conical clearance surface extending between the first curved cutting-edge region and the perimeter of the bottom surface. 
     
     
         3 . The cutting insert of  claim 1 , further comprising a second conical clearance surface extending between the second curved cutting-edge region and the perimeter of the bottom surface. 
     
     
         4 . The cutting insert of  claim 1 , wherein each convex cutting edge comprises a first straight cutting-edge region disposed between the second curved cutting-edge region and the nose corner region. 
     
     
         5 . The cutting insert of  claim 4 , further comprising a first planar clearance surface extending between the first straight cutting-edge region and the perimeter of the bottom surface. 
     
     
         6 . The cutting insert of  claim 4 , wherein each convex cutting edge comprises a second straight cutting-edge region disposed between the first straight cutting-edge region and the nose corner region. 
     
     
         7 . The cutting insert of  claim 6 , further comprising a second planar clearance surface extending between the second straight cutting-edge region and the perimeter of the bottom surface. 
     
     
         8 . The cutting insert of  claim 6 , wherein each convex cutting edge comprises a third straight cutting-edge region disposed between the second straight cutting-edge region and the nose corner region. 
     
     
         9 . The cutting insert of  claim 8 , further comprising a third planar clearance surface extending between the third straight cutting-edge region and the perimeter of the bottom surface. 
     
     
         10 . The cutting insert of  claim 1 , wherein the first curved cutting-edge region comprises a circular arc having a radius greater than or equal to two times the radius of the largest circle that may be inscribed on the top surface. 
     
     
         11 . The cutting insert of  claim 1 , wherein each convex cutting edge comprises at least one of a circular arc, a portion of an ellipse, a portion of a parabola, a multi-segment spline curve, a straight line. 
     
     
         12 . The cutting insert of  claim 1 , wherein the nose corner region comprises at least one of a circular arc, a series of circular arcs, and a multi-segment spline curve. 
     
     
         13 . The cutting insert of  claim 1 , further comprising chip breaking geometry on the top surface. 
     
     
         14 . A cutting insert, comprising:
 a top surface;   a bottom surface with a perimeter that is less than a perimeter of the top surface;   a plurality of side surfaces connecting the top surface and the bottom surface;   a convex cutting edge formed at an intersection between each side surface and the top surface; and   a nose corner region connecting adjacent convex cutting edges,   wherein each convex cutting edge comprises a first curved cutting-edge region formed with a radius greater than or equal to a radius of the largest circle that may be inscribed on the top surface,   wherein each convex cutting edge comprises a second curved cutting-edge region disposed between the first curved cutting-edge region and the nose corner region, the second curved cutting-edge region formed with a radius less than or equal to a diameter of the largest circle that may be inscribed on the top surface, and   wherein each convex cutting edge comprises one or more straight cutting-edge regions disposed between the second curved cutting-edge region and the nose corner region.   
     
     
         15 . The cutting insert of  claim 14 , further comprising a first conical clearance surface extending between the first curved cutting-edge region and the perimeter of the bottom surface. 
     
     
         16 . The cutting insert of  claim 15 , further comprising a second conical clearance surface extending between the second curved cutting-edge region and the perimeter of the bottom surface. 
     
     
         17 . The cutting insert of  claim 15 , further comprising a first planar clearance surface extending between a first straight cutting-edge region and the perimeter of the bottom surface. 
     
     
         18 . The cutting insert of  claim 17 , further comprising a second planar clearance surface extending between a second straight cutting-edge region and the perimeter of the bottom surface. 
     
     
         19 . The cutting insert of  claim 14 , wherein each convex cutting edge comprises at least one of a circular arc, a portion of an ellipse, a portion of a parabola, a multi-segment spline curve, a straight line. 
     
     
         20 . The cutting insert of  claim 14 , wherein the nose corner region comprises at least one of a circular arc, a series of circular arcs, and a multi-segment spline curve. 
     
     
         21 . The cutting insert of  claim 14 , further comprising chip breaking geometry on the top surface.